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TC Protocol optimization: A quantitative approach
Abstracts / Physica Medica 32 (2016) 251–273
TC PROTOCOL OPTIMIZATION: A QUANTITATIVE APPROACH M. Biondi a,*, A. La Penna b, E. Vanzi a, L.N. Mazzoni a, G. De Otto a, G.M. Belmonte a, E. Foderà b, R. Martini b, G. Imbriaco b, F.S. Carbone c, A. Guasti d, L. Volterrani b, F. Banci Buonamici a a Department of Medical Physics, University Hospital of Siena, Siena, Italy b Department of Medical, Surgical and Neurosciences, University of Siena, Siena, Italy c Department of Diagnostic Imaging, University Hospital of Siena, Siena, Italy d Department of Medical Physics, Azienda USL Toscana sud est, Siena, Italy ⇑ Corresponding author.
Introduction. Every year the number of performed CT scans is dramatically increasing, so that protocol optimization in terms of dose and image quality is mandatory. Purpose. To evaluate the efficacy of a novel objective method to compare different CT protocols based on a functional (F) encompassing signal to noise ratio (SNR), low contrast resolution (LCR) and CTDI. Materials and methods. Catphan 600 was scanned with a Discovery 750 (GE healthcare) 64 slices CT scanner varying tube voltage (kV = 100, 120, 140) and noise index (NI = 8, 12). Images were reconstructed using the standard FBP algorithm. LCR was assessed with CTP515 analysis, SNR was evaluated for every CTP404 insert And CTDI was recorded from consolle. An F value was calculated for each protocol as follows: P LCR CTDI wins SNRprot ins F prot ðaÞ ¼ ð1 aÞ þ þa prot LCR CTDI prot SNRins where average values were computed over all the protocols used and a is weighting factor which was varied between 0 and 1 to differently balance dose and quality aspects. For each selected a higher F values are associated with a better trade-off between image quality and dose. Results. For a values between 0 and 0.6 higher F values were obtained for 120 kV/8 NI; for 0.7 6 a 6 1 the best trade-off was found for 100 kV/12 NI. Conclusion. The proposed CT protocol optimization approach provided an objective way to balance between dose and image quality in phantom. Further studies are in progress to assess the performances of the method in vivo. Disclosure. Authors disclose any relationship that may bias their presentation. http://dx.doi.org/10.1016/j.ejmp.2016.07.563
WEB BASED NATIONAL PATIENT DOSE SURVEY IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY. PRELIMINARY RESULTS AND ANALYSIS OF SURVEY PERFORMANCE F. Simeonov a,*, D. Kostova-Lefterova a, D. Ivanova a, J. Vassileva b a National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria b International Atomic Energy Agency, Vienna, Austria ⇑ Corresponding author.
Introduction. According to the Bulgarian regulation for radiation protection of medical exposure, the National Centre of Radiobiology and Radiation Protection (NCRRP) is responsible for performing national dose surveys in diagnostic and interventional radiology and nuclear medicine and for establishing of national diagnostic reference levels (DRLs).
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Purpose. In the period 2014–15 NCRRP have developed web based platform with main goal to establish new national DRLs by collecting data from most of the facilities in the country. Materials and methods. In collaboration with software company centralized database was developed. The database can be accessed via internet browser, allowing pre-registered user remote sending of survey data. Electronic questionnaires with the necessary technical and dosimetric information were prepared. Short but clear manuals are also included to guide users, and to minimize errors. Since many of the X-ray systems in Bulgaria are still analogue, the platform at this stage also allows manually enter patient data by the user. Results. Users from Bulgarian hospitals was trained and encouraged to enter data. During the test period more than 300 individual patient data sets, from 8 clinical departments, were sent in the database of platform. Currently medical physicists and radiographers from more than 20 clinical departments collect and enter data in the platform. Conclusion. Patient data gathered from number of hospitals and different type of examination was used to test the platform. Every hospital or clinical department participated in the survey can establish the local DRLs and initiate optimization of their own protocol. http://dx.doi.org/10.1016/j.ejmp.2016.07.564
LOCAL DIAGNOSTIC REFERENCE LEVELS IN CHILDREN’S CT EXAMINATIONS ACCORDING TO THE NEW EUROPEAN GUIDELINES Makri Triantafyllia *, Tsilimidou Artemis, Syrgiamiotis Vasilis, Xatzigiorgi Christiana Radiological Imaging Department, General Pediatric Hospital of Athens ‘‘Agia Sofia”, Greece ⇑ Corresponding author. Introduction. The determination of paediatric DRLs is a difficult task mostly due to the large variation in children’s somatometric characteristics. In children until now the DRLs were expressed as a function of patient age. The newest EU Guidelines on paediatric DRLs recommend that the grouping parameters should be patient weight for all body examinations and patient age for all head examinations. Purpose. This study intends to express the local DRLs for CT examinations in accordance to new EU recommendations for patient grouping parameters: age and weight. Materials and methods. Exposure parameters and dosimetric data such as CTDIvol and DLP values, were recorded from system’s console for 396 routine Head CT, 162 Thorax CT and 92 Abdomen CT examinations, along with data concerning children’s age and somatometric characteristics. Two parameters for the data grouping were applied: age, and weight. The DRLs were calculated for the considered examinations, for five age groups (0–1 month, 1–12 months, 1–5, 5–10 and 10–15 years) and five weight groups (<5, 5–15, 15–30, 30–50, 50–80 kg). Results. The relationship of paediatric dose with age and somatometric characteristics was studied in detail. Dosimetric data were found to vary significantly among age and weight groups for the same type of examination. Both CTDIvol and the DLP values increase with age and weight. DLP seems to represent a better index of patient dose. Conclusion. Patient dose levels may vary considerably as a function of age, size or weight and therefore DRLs for several ages, size or weight groups need to be defined. Disclosure. None. http://dx.doi.org/10.1016/j.ejmp.2016.07.565
TC PROTOCOL OPTIMIZATION: A QUANTITATIVE APPROACH M. Biondi a,*, A. La Penna b, E. Vanzi a, L.N. Mazzoni a, G. De Otto a, G.M. Belmonte a, E. Foderà b, R. Martini b, G. Imbriaco b, F.S. Carbone c, A. Guasti d, L. Volterrani b, F. Banci Buonamici a a Department of Medical Physics, University Hospital of Siena, Siena, Italy b Department of Medical, Surgical and Neurosciences, University of Siena, Siena, Italy c Department of Diagnostic Imaging, University Hospital of Siena, Siena, Italy d Department of Medical Physics, Azienda USL Toscana sud est, Siena, Italy ⇑ Corresponding author.
Introduction. Every year the number of performed CT scans is dramatically increasing, so that protocol optimization in terms of dose and image quality is mandatory. Purpose. To evaluate the efficacy of a novel objective method to compare different CT protocols based on a functional (F) encompassing signal to noise ratio (SNR), low contrast resolution (LCR) and CTDI. Materials and methods. Catphan 600 was scanned with a Discovery 750 (GE healthcare) 64 slices CT scanner varying tube voltage (kV = 100, 120, 140) and noise index (NI = 8, 12). Images were reconstructed using the standard FBP algorithm. LCR was assessed with CTP515 analysis, SNR was evaluated for every CTP404 insert And CTDI was recorded from consolle. An F value was calculated for each protocol as follows: P LCR CTDI wins SNRprot ins F prot ðaÞ ¼ ð1 aÞ þ þa prot LCR CTDI prot SNRins where average values were computed over all the protocols used and a is weighting factor which was varied between 0 and 1 to differently balance dose and quality aspects. For each selected a higher F values are associated with a better trade-off between image quality and dose. Results. For a values between 0 and 0.6 higher F values were obtained for 120 kV/8 NI; for 0.7 6 a 6 1 the best trade-off was found for 100 kV/12 NI. Conclusion. The proposed CT protocol optimization approach provided an objective way to balance between dose and image quality in phantom. Further studies are in progress to assess the performances of the method in vivo. Disclosure. Authors disclose any relationship that may bias their presentation. http://dx.doi.org/10.1016/j.ejmp.2016.07.563
WEB BASED NATIONAL PATIENT DOSE SURVEY IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY. PRELIMINARY RESULTS AND ANALYSIS OF SURVEY PERFORMANCE F. Simeonov a,*, D. Kostova-Lefterova a, D. Ivanova a, J. Vassileva b a National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria b International Atomic Energy Agency, Vienna, Austria ⇑ Corresponding author.
Introduction. According to the Bulgarian regulation for radiation protection of medical exposure, the National Centre of Radiobiology and Radiation Protection (NCRRP) is responsible for performing national dose surveys in diagnostic and interventional radiology and nuclear medicine and for establishing of national diagnostic reference levels (DRLs).
261
Purpose. In the period 2014–15 NCRRP have developed web based platform with main goal to establish new national DRLs by collecting data from most of the facilities in the country. Materials and methods. In collaboration with software company centralized database was developed. The database can be accessed via internet browser, allowing pre-registered user remote sending of survey data. Electronic questionnaires with the necessary technical and dosimetric information were prepared. Short but clear manuals are also included to guide users, and to minimize errors. Since many of the X-ray systems in Bulgaria are still analogue, the platform at this stage also allows manually enter patient data by the user. Results. Users from Bulgarian hospitals was trained and encouraged to enter data. During the test period more than 300 individual patient data sets, from 8 clinical departments, were sent in the database of platform. Currently medical physicists and radiographers from more than 20 clinical departments collect and enter data in the platform. Conclusion. Patient data gathered from number of hospitals and different type of examination was used to test the platform. Every hospital or clinical department participated in the survey can establish the local DRLs and initiate optimization of their own protocol. http://dx.doi.org/10.1016/j.ejmp.2016.07.564
LOCAL DIAGNOSTIC REFERENCE LEVELS IN CHILDREN’S CT EXAMINATIONS ACCORDING TO THE NEW EUROPEAN GUIDELINES Makri Triantafyllia *, Tsilimidou Artemis, Syrgiamiotis Vasilis, Xatzigiorgi Christiana Radiological Imaging Department, General Pediatric Hospital of Athens ‘‘Agia Sofia”, Greece ⇑ Corresponding author. Introduction. The determination of paediatric DRLs is a difficult task mostly due to the large variation in children’s somatometric characteristics. In children until now the DRLs were expressed as a function of patient age. The newest EU Guidelines on paediatric DRLs recommend that the grouping parameters should be patient weight for all body examinations and patient age for all head examinations. Purpose. This study intends to express the local DRLs for CT examinations in accordance to new EU recommendations for patient grouping parameters: age and weight. Materials and methods. Exposure parameters and dosimetric data such as CTDIvol and DLP values, were recorded from system’s console for 396 routine Head CT, 162 Thorax CT and 92 Abdomen CT examinations, along with data concerning children’s age and somatometric characteristics. Two parameters for the data grouping were applied: age, and weight. The DRLs were calculated for the considered examinations, for five age groups (0–1 month, 1–12 months, 1–5, 5–10 and 10–15 years) and five weight groups (<5, 5–15, 15–30, 30–50, 50–80 kg). Results. The relationship of paediatric dose with age and somatometric characteristics was studied in detail. Dosimetric data were found to vary significantly among age and weight groups for the same type of examination. Both CTDIvol and the DLP values increase with age and weight. DLP seems to represent a better index of patient dose. Conclusion. Patient dose levels may vary considerably as a function of age, size or weight and therefore DRLs for several ages, size or weight groups need to be defined. Disclosure. None. http://dx.doi.org/10.1016/j.ejmp.2016.07.565